The aim of the authors' work was to study the impact of monochloramine on sessile and planktonic Legionella pneumophila populations. The authors produced Legionella biofilms on glass beads (0.5 mm diameter) in buffered-yeast extract (BYE) broth. Bacteria were grown for one week at 37°C, under static conditions. Planktonic cells were obtained in same growth conditions without glass beads. Planktonic and sessile cells were washed twice with sterile water and then treated with 0.25 to 10 mg liter-1 monochloramine solutions. Sessile bacteria were collected from glass beads by sonication and enumerated on buffered charcoal yeast extract (BCYE) agar. In order to detect metabolic activity in viable-but-nonculturable (VBNC) cells, planktonic L. pneumophila Lens cells were treated with 0.75 mg liter-1 of monochloramine in order to obtain no culturable cells. After 8 days in the resting medium, the authors were able to detect esterase activity and membrane integrity by fluorescence microscopy using the ChemChrom V6 substratum (Chemunex) in samples without culturable cells. This demonstrates that VBNC cells produced by monochloramine retained metabolic activity. Recovery of culturability was observed for sessile bacteria treated with 1 mg liter-1 of monochloramine and coincubated with Acanthamoeba castellanii.

An outbreak of Legionnaires' disease (LD) occurred in August 2004 in Sweden in the town of Lidköping, by Lake Vänern. Two genotypes of Legionella pneumophila serogroup (sg) 1 were found by culture in patient samples, and one belonging to subgroup Benidorm (genotype A) and the other to subgroup Bellingham (genotype B). The indirect immunofluorescent antibody technique (IFAT) is still a standard method for antibody assay in patients with legionellosis, allowing for the screening of antibodies against several species and subtypes of Legionella. A serological study was therefore undertaken to assess the impact of the legionella outbreak on all pneumonia cases that occurred in the town. Patient samples were also tested for antibodies against other atypical pneumonia agents, i.e. Mycoplasma pneumoniae and Chlamydophila pneumoniae. Local experience in the laboratory using more than one subgroup of antigen had been shown earlier to increase sensitivity. Optimal sensitivity of immunofluorescent antibody tests in serological diagnosis of L. pneumphila sg 1 infections requires the use of an antigen subgroup that is in agreement with the antigenic setup of the epidemic strain.

The European Surveillance Scheme for Travel Associated Legionnaires’ Disease (EWGLINET) has helped strengthen European national surveillance systems and improve case detection and reporting in travel-associated cases. The guidance and legislation introduced in England and Wales over the past 25 years aims to ensure that all relevant systems are properly installed and maintained and that investigation of these systems (e.g., wet cooling towers) in an outbreak situation is as efficient as possible. These measures are aimed at reducing the absolute number of cases of Legionnaires’ disease. England and Wales’ annual case reports severely underrepresent the true annual incidence of Legionnaires’ disease. The urinary antigen test was introduced in England and Wales in the 1990s and is now the primary diagnostic method for 80% of English and Welsh cases of Legionnaires’ disease. The test is quick and easy to perform and might therefore be enabling countries to detect milder cases of the disease that would otherwise have gone undiagnosed. However, in England and Wales the number of cases has remained relatively constant despite the increasing use of the test. The simple trend of an increasing number of cases of Legionnaires’ disease in England and Wales over the past 25 years masks a more complicated picture. Reporting systems that suffer from underdiagnosis and underreporting are likely to register an increase in case reports (as ascertainment improves) before any actual decrease from improved control and prevention in case numbers is detected.

Community-acquired and hospital-acquired legionellosis have been occasionally reported in Korea since the recognition of an outbreak of Pontiac fever in 1984. However, there was a lack of epidemiological information on the diagnosed patients that could be used as serological evidence. Researchers analyzed the epidemiological and clinical data and antibiotic treatment records for the patients diagnosed serologically as having legionellosis in Korea during 1999 to 2002. The common clinical symptoms included fever, cough, sputum, and dyspnea. Twenty-eight patients (25.9%) showed reactivity for Legionella gormanii, and 14 patients (13.0%) were associated with L. pneumophila serogroup 1 according to serological tests. Most of the legionellosis cases diagnosed with serological methods in Korea show epidemiological aspects similar to those reported in other countries. In sero-diagnosis of this study, it is remarkable that L. gormanii was the most prevalent species in Korea. Therefore, L. gormanii infection as well as other Legionella species other than L. pneumophila should be taken into consideration when serological diagnosis is performed in Korea.

This chapter compares human leukocyte antigen (HLA) frequency and HLA haplotype frequency in Legionella-positive patients with frequencies in healthy individuals from a local panel (control group). Sputum, bronchoalveolar lavage (BAL), or urine obtained from 114 patients after solid organ (heart, kidney, liver, pancreas) transplantation were examined for the presence of Legionella by using the culture method (sputum, BAL), and the direct fluorescent antibody assay method (sputum, BAL), and by the detection of urinary antigen (urine) during the 4 months after transplantation. A buffered charcoal-yeast extract medium (OXOID) was the culture method used in parallel with BMPA and GVPC selective supplements. Legionella serotypes were determined by using microagglutination test. The monoclonal antibody of MONOFLUO L. pneumophila IFA test kit was used for the direct fluorescent-antibody assay method. The urinary antigen was detected by using Legionella Urin antigen enzyme immunoassay. Differences were found in HLA-A antigen frequencies and HLA-B antigen frequencies between Legionella-positive patients and a control group. Differences in HLA A-B haplotypes and HLA A-B-DR haplotypes were not statistically significant between healthy individuals and Legionella-positive patients. Several published reports suggest that natural resistance or susceptibility to infection with Legionella might be genetically determined. However, no significant difference in HLA class II antigens and the frequencies of haplotypes HLA A-B and HLA A-B-DR was found between both defined groups.

Legionellosis is a new infectious disease emerging in Poland although not yet registered. A Polish working group aimed at selecting laboratory methods for investigating human Legionella infections and detecting bacterium in the environment. The specimens from patients were examined for Legionella antigen in urine and for the level of antibodies to Legionella pneumophila serogroup 1 in patient sera. The standard commercial BIOTEST was used for the determination of Legionella antigen in urine. The procedure was evaluated according to the European program of the European Working Group for Legionella Infections for quality of testing of Legionella antigen determination in urine. Human serum samples of 180 patients with pneumonia and other pulmonary infectious diseases were collected and examined by microagglutination test. The antibodies to L. pneumophila serogroup 1 titer as high as 2,048 were found in only 2 of 69 sera from patients with atypical pneumonia: in one convalescent patient's serum and in serum of one nosocomial case with symptoms of pneumonia. The urine antigen of Legionella tests determined by the enzyme immunoassay method was also positive in both cases. The risk of L. pneumophila infection still seems to be low for the general population in Poland. It might be higher for some groups, including patients in rehabilitation and transplant units, and for staff in certain institutions such as hospitals.